Control valve assembly

Abstract

A subassembly for a high pressure fuel injector control valve includes a control valve member and a sleeve attached to a stem of the control valve member, the sleeve extending along at least a partial axial length of the stem of the control valve member, and wherein a clearance, provided between the sleeve and the control valve member, is in fluid communication with the control chamber such that during use, pressure compensation occurs, as the sleeve is caused to expand and seal against the control valve bore, thereby preventing leakage of fuel within the control valve assembly.

The invention claimed is: 
     
       1. A subassembly for a control valve for a fuel injector;
 the subassembly comprising a control valve member and a sleeve attached to a stem of the control valve member; 
 wherein the subassembly is located within a bore of a control valve body, and wherein the subassembly and the control valve body are arranged for relative movement with one another, between a closed position, wherein a flow of fuel between a fuel passage and a fuel return line via a control chamber is prevented, and an open position, wherein the flow of fuel is enabled; 
 wherein the sleeve extends along at least a partial axial length of the stem of the control valve member; 
 and wherein a clearance, provided between the sleeve and the control valve member, is in fluid communication with the control chamber. 
 
     
     
       2. A subassembly as claimed in  claim 1  wherein, when the subassembly and the control valve body are in the closed position, an axial distance from an end face of the stem distal from the control chamber, to an end face of the sleeve proximate the control chamber, is less than an axial distance from the end face of the stem to a base of an entrance from the fuel passage to the control chamber,
 and wherein an axial distance from the end face of the sleeve to the base of the entrance of the fuel passage, is greater than a distance of travel of the control valve member between the open position and the closed position. 
 
     
     
       3. A subassembly as claimed in  claim 2  wherein the stem comprises at least one radial protrusion, wherein the at least one protrusion contacts an inner surface of the sleeve. 
     
     
       4. A subassembly as claimed in  claim 2  wherein the sleeve is attached to the control valve member at least by a weld between an enlarged portion of the stem and a contact point on an inner surface of the stem. 
     
     
       5. A subassembly as claimed in  claim 2  wherein the sleeve is maintained in position on the control valve member by a sealing ring located in a groove recess provided on an enlarged portion of the stem. 
     
     
       6. A subassembly as claimed in  1  wherein the stem comprises at least one radial protrusion, wherein the at least one protrusion contacts an inner surface of the sleeve. 
     
     
       7. A subassembly as claimed in  claim 1  wherein the sleeve is attached to the control valve member at least by a weld between an enlarged portion of the stem and a contact point on an inner surface of the stem. 
     
     
       8. A subassembly as claimed in  claim 1  wherein the sleeve is maintained in position on the control valve member by a sealing ring located in a groove recess provided on an enlarged portion of the stem. 
     
     
       9. A subassembly as claimed in  claim 1  wherein:
 the control valve member includes a control valve member face; 
 the control valve body includes a control valve body face; 
 relative movement of the subassembly and the control valve body to the closed position causes the control valve member face to engage the control valve body face such that engagement of the control valve member face with the control valve body face prevents flow of fuel between the fuel passage and the fuel return line via the control chamber; and 
 relative movement of the subassembly and the control valve body to the open position causes the control valve member face to be spaced apart from the control valve body face such that spacing apart of the valve member face from the control valve body face enables flow of fuel between the fuel passage and the fuel return line via the control chamber. 
 
     
     
       10. A subassembly as claimed in  claim 1  wherein the sleeve is moveable with the valve member and relative to the control valve body during relative movement of the subassembly and the control valve body. 
     
     
       11. A control valve assembly for a fuel injector, the control valve assembly comprising:
 a control valve body; and 
 a subassembly comprising a control valve member and a sleeve attached to a stem of the control valve member; 
 wherein the subassembly is located within a bore of a control valve body, and wherein the subassembly and the control valve body are arranged for relative movement with one another, between a closed position, wherein a flow of fuel between a fuel passage and a fuel return line via a control chamber is prevented, and an open position, wherein the flow of fuel is enabled; 
 wherein the sleeve extends along at least a partial axial length of the stem of the control valve member; 
 and wherein a clearance, provided between the sleeve and the control valve member, is in fluid communication with the control chamber. 
 
     
     
       12. A control valve assembly as claimed in  claim 11  wherein, when the subassembly and the control valve body are in the closed position, an axial distance from an end face of the stem distal from the control chamber, to an end face of the sleeve proximate the control chamber, is less than an axial distance from the end face of the stem to a base of an entrance from the fuel passage to the control chamber,
 and wherein an axial distance from the end face of the sleeve to the base of the entrance of the fuel passage, is greater than a distance of travel of the control valve member between the open position and the closed position. 
 
     
     
       13. A control valve assembly as claimed in  claim 12  wherein the stem comprises at least one radial protrusion, wherein the at least one protrusion contacts an inner surface of the sleeve. 
     
     
       14. A control valve assembly as claimed in  claim 12  wherein the sleeve is attached to the control valve member at least by a weld between an enlarged portion of the stem and a contact point on an inner surface of the stem. 
     
     
       15. A control valve assembly as claimed in  claim 12  wherein the sleeve is maintained in position on the control valve member by a sealing ring located in a groove recess provided on an enlarged portion of the stem. 
     
     
       16. A control valve assembly as claimed in  11  wherein the stem comprises at least one radial protrusion, wherein the at least one protrusion contacts an inner surface of the sleeve. 
     
     
       17. A control valve assembly as claimed in  claim 11  wherein the sleeve is attached to the control valve member at least by a weld between an enlarged portion of the stem and a contact point on an inner surface of the stem. 
     
     
       18. A control valve assembly as claimed in  claim 11  wherein the sleeve is maintained in position on the control valve member by a sealing ring located in a groove recess provided on an enlarged portion of the stem. 
     
     
       19. A control valve assembly as claimed in  claim 11  wherein
 the control valve member includes a control valve member face; 
 the control valve body includes a control valve body face; 
 relative movement of the subassembly and the control valve body to the closed position causes the control valve member face to engage the control valve body face such that engagement of the control valve member face with the control valve body face prevents flow of fuel between the fuel passage and the fuel return line via the control chamber; and 
 relative movement of the subassembly and the control valve body to the open position causes the control valve member face to be spaced apart from the control valve body face such that spacing apart of the valve member face from the control valve body face enables flow of fuel between the fuel passage and the fuel return line via the control chamber. 
 
     
     
       20. A control valve assembly as claimed in  claim 11  wherein the sleeve is moveable with the valve member and relative to the control valve body during relative movement of the subassembly and the control valve body.